硫化物固体电解质材料的制备改性与应用研究
发布时间：2019-05-16 22:55
【摘要】：在无机固体电解质中,硫化物固体电解质有着明显的优势:锂离子电导率高;对金属锂具有良好的稳定性,电化学窗口比较宽(6V vs.Li/Li~+)。因此,硫化物固体电解质在新一代锂离子电池的应用上具有极好的前景。虽然硫化物固体电解质具有以上各种优势,但是这类材料离实际应用还有一些问题需要解决。如部分二元硫化物固体电解质锂离子电导率还不够高,三元硫化物固体电解质的离子电导率高,但对金属锂不稳定。针对上述问题,本论文从硫化物电解质材料的掺杂改性及复合处理的研究入手,寻找提高硫化物电解质离子电导率,改善硫化物电解质对锂稳定性的方法,主要研究内容如下:(1)75Li_2S·25P_2S_5玻璃材料由高能球磨法制备,75Li_2S·25P_2S_5玻璃陶瓷材料由适当热处理制得。在球料比45/1,球磨转速500 rpm的条件下,得出最佳球磨时间为12 h;最佳热处理温度为270 ℃,最佳热处理时间为4 h。所制备的75Li_2S·25P_2S_5玻璃陶瓷是由粒径一到数个微米的球状颗粒组成。75Li_2S·25P_2S_5玻璃陶瓷的最高室温离子电导率为3.67×10~(-4)Scm~(-1)。(2)75Li_2S·(25-x)P_2S_5·x P_2O_5(mol%)玻璃陶瓷固态电解质由合适的高能球磨法及后续热处理工艺制备。掺杂了1%P_2O_5所得的电解质材料在室温下的离子电导率为8×10-4 S cm~(-1)。电导率提升的原因在于氧原子的引入,在玻璃体网络中是以共价键链接的,P-O键相比于P-S键具有更强的结合,从而导致P-O键的结构单元对锂离子具有相对较弱的作用力,有利于锂离子的快速迁移。新制备的75Li_2S·24P_2S_5·1P_2O_5对锂金属表现出极好的电化学稳定性与兼容性。全固态锂电池LiCoO_2/75Li_2S·24P_2S_5·1P_2O_5/Li在0.1C下的放电容量为10~9mAhg~(-1),以及25 ℃下循环30圈后85.2%的容量保持率。(3)将二元硫化物固体电解质75Li_2S·24P_2S_5·1P_2O_5(LPOS)的非晶前驱体与三元硫化物电解质Li_(10)Ge P_2S_(12)(LGPS)前驱体按不同质量比均匀混合后,在270 ℃下进行烧结制备得到系列新型固体电解质材料(1-ω%)LPOS-ω%(t-LGPS)(ω=3,5,7,10)。当ω=5时,制得的新型固体电解质95%LPOS-5%(t-LGPS)在室温下具有最佳的离子电导率1.0×10~(-3) S cm~(-1)。采用XRD,EIS,SEM等手段对该新型电解质材料的结构、形貌及电化学性能等进行了系统表征,并对电导率提高的机理进行了探讨。构建的全固态锂电池LiCoO_2/95%LPOS-5%(t-LGPS)/Li表现出良好的电池性能,在25 ℃,0.1C下,电池首周放电容量为115.7 mAhg-1,循环20圈后仍有80.38%的容量保持率。
[Abstract]:Among inorganic solid electrolytes, sulfide solid electrolytes have obvious advantages: high conductivity of lithium ion, good stability to lithium metal, wide electrochemical window (6V vs.Li/Li~). Therefore, sulfides solid electrolytes have an excellent prospect in the application of new generation lithium ion batteries. Although sulfides solid electrolytes have the above advantages, there are still some problems to be solved from the practical application of these materials. For example, the lithium ion conductivity of some binary sulfide solid electrolytes is not high enough, and the ion conductivity of ternary sulfide solid electrolytes is high, but it is unstable to lithium metal. In order to solve the above problems, this paper starts with the study of doping modification and composite treatment of sulfide electrolyte materials, and finds out the methods to improve the ionic conductivity of sulfide electrolyte and improve the stability of sulfide electrolyte to lithium. The main research contents are as follows: (1) 75Li _ 2S 路25p _ 2S_5 glass material was prepared by high energy ball milling, and 75Li _ 2S 路25p _ 2S_5 glass-ceramic material was prepared by proper heat treatment. When the ratio of ball to material is 45 脳 1 and the speed of ball milling is 500 rpm, the optimum milling time is 12 h, the optimum heat treatment temperature is 270 鈩，
本文编号：2478614
[Abstract]:Among inorganic solid electrolytes, sulfide solid electrolytes have obvious advantages: high conductivity of lithium ion, good stability to lithium metal, wide electrochemical window (6V vs.Li/Li~). Therefore, sulfides solid electrolytes have an excellent prospect in the application of new generation lithium ion batteries. Although sulfides solid electrolytes have the above advantages, there are still some problems to be solved from the practical application of these materials. For example, the lithium ion conductivity of some binary sulfide solid electrolytes is not high enough, and the ion conductivity of ternary sulfide solid electrolytes is high, but it is unstable to lithium metal. In order to solve the above problems, this paper starts with the study of doping modification and composite treatment of sulfide electrolyte materials, and finds out the methods to improve the ionic conductivity of sulfide electrolyte and improve the stability of sulfide electrolyte to lithium. The main research contents are as follows: (1) 75Li _ 2S 路25p _ 2S_5 glass material was prepared by high energy ball milling, and 75Li _ 2S 路25p _ 2S_5 glass-ceramic material was prepared by proper heat treatment. When the ratio of ball to material is 45 脳 1 and the speed of ball milling is 500 rpm, the optimum milling time is 12 h, the optimum heat treatment temperature is 270 鈩，
本文编号：2478614
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